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Sewer Division
Private Inflow Source Removal Program

Program History
The Town of Greenwich is under orders from the U.S. Department of Justice, the U.S. Environmental Protection Agency (USEPA), and the Connecticut Department of Energy & Environmental Protection (CTDEEP) to remove inflow sources from the Town's sanitary sewer collection system and continues this program as part of the Sewer Division's Annual Maintenance Program.

How is this being addressed? This program is ongoing, with the remainder of Greenwich under investigation in our second investigation phase. The letters going out to residents include those for:

  • Confirmed illegal connection: where the physical connection of an illegal sources to the sanitary collection system was documented during an inspection. This letter mandates disconnection.
  • Flexible connection: where the sump pump discharge is flexibly connected to its discharge point, even if the current discharge point is acceptable. This letter mandates installation of hard piping, to prevent future connection to an inappropriate location.
  • Suspected connection: where preliminary investigation in the area strongly indicates an illegal connection. This letter mandates an inspection to perform testing which will either negate or confirm the connection.
  • Request for inspection: where initial attempts to schedule an inspection were not successful, for whatever reason. This letter mandates that the property owner schedule an inspection.

What is inflow? Inflow is ground or storm water discharged by connection to the sanitary sewer through basement sump pumps, floor drains, roof leaders, foundation and yard drains, catch basins and condensate lines, etc. These types of connections to the sanitary sewer are illegal as dictated by the Town Sewer Code. Inflow sources contribute to high flows in the system, resulting in sanitary sewer overflows. Such overflows can have a detrimental effect on the ecology of the Long Island Sound, reduce water quality for recreation, and create unhealthy environmental conditions for Town residents.

How is it Found? To help identify inflow sources, the Town of Greenwich embarked on a major investigation of its collection system. In the first phase, flow monitoring was conducted in several neighborhoods including Belle Haven, Byram, Old Greenwich, and Riverside. As a result of this monitoring, particular areas were targeted for more specific investigation in the form of smoke testing and building inspections. Additional inspections have identified other areas and the town is starting a second phase of flow monitoring to help identify sources.

How much was found?: From these inflow investigations, we found a total of 181 sump pumps and 30 drains directly connected to the sewer. Another ? sump pumps have the potential to be connected to the sewer because of an unknown discharge location or flexible discharge pipe. The confirmed illegal connections have the potential to discharge 1.55 million gallons of inflow during a storm, approximately 15% of the Grass Island Wastewater Treatment Plant's average daily flow. This is clearly a significant issue for our collection system and treatment plant facilities.  

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